This application is related to the following co-pending applications filed concurrently herewith by the same Applicants and assigned to the same Assignee: “DOUBLE EFFICIENCY SHEET BUFFER MODULE AND MODULAR PRINTING SYSTEM WITH DOUBLE EFFICIENCY SHEET BUFFER MODULE” Ser. No. 12/413,802 and “SPACE EFFICIENT MULTI-SHEET BUFFER MODULE AND MODULAR PRINTING SYSTEM” Ser. No. 12/413,876. The complete disclosures of these co-pending applications are incorporated in their entirety herein by reference.
Embodiments herein generally relate to printing systems and, more particularly, to embodiments of a combined sheet buffering and inverting device that can be incorporated into a discrete module within a modular multi-marking engine printing system or into a standalone printing system.
Sheets being processed within a modular printing system may benefit from buffering and/or inverting after processing by multiple heterogeneous printing engines. For example, U.S. patent application Ser. No. 12/211,853 of Bober et al., filed on Sep. 17, 2008, and U.S. patent application Ser. No. 12/331,768 of Mandel et al., filed on Dec. 10, 2008 (both of which are assigned to Xerox Corporation of Norwalk, Conn., USA, and incorporated herein by reference in their entirety) both disclose electrostatographic printing systems comprising multiple modules (i.e., discrete interchangeable units). Each module comprises one or more of the printing system's functional components (e.g., sheet feeders, printing engines, finishers, etc.) structurally self-contained within its own supporting frame and housing (i.e., cabinet).
Oftentimes multi-page documents contain both single color (i.e., monochrome) pages and multi-color pages. Since it is more cost and time efficient to print single color pages using a single color (i.e., monochrome) printing engine vice a multi-color printing engine, modular printing systems incorporating heterogeneous printing engine modules (e.g., a single color and multi-color printing engine modules) in a tightly integrated parallel printing (TIPP) architecture have been developed (e.g., see U.S. patent application Ser. No. 12/211,853 of Bober et al. and U.S. patent application Ser. No. 12/331,768 of Mandel et al., incorporated by reference above). Such modular printing systems can print multi-page documents, having single color and multi-color pages in simplex and/or duplex format. To ensure that the various single color and multi-color pages are printed on print media sheets by the appropriate printing engine(s), a sorting process is performed.
Once printed, the single color and multi-color pages are merged back into a single stream in order to output the finished document. However, timing of sheet output from the different print engines to ensure proper page merging (i.e., to ensure that pages are in the proper order) presents a problem for a number of reasons. For example, since multi-color print engines are typically more costly to run and since multi-page documents typically have significantly more text-only pages than multi-color pages, it is more cost efficient to print all or batches of multi-color pages together. This minimizes the number of non-printing on-off and warm-up cycles performed by the multi-color printing engine during a single print job, but results in multi-color pages being printed out of order and, particularly, early. Timing of sheet output and also proper sheet orientation at output are further made difficult as a result of duplex printing and mixed printing (i.e., when a single sheet requires printing by one side by a single color printing engine and on the opposite side by a multi-color printing engine). Thus, it would be advantageous to provide a sheet buffering and inverting device that can be incorporated into a discrete module of a modular printing system in order to ensure sheets are properly merged and oriented after processing by multiple printing engines.
Sheets being processed within a standalone printing system may benefit from buffering and/or inverting prior to printing by a single printing engine. That is, sheets may need to be buffered (i.e., staged, temporarily held, etc.) until the printing engine is ready to receive them. Additionally, for duplex printing, sheets may need to be inverted prior to passing through the printing engine a second time. Thus, it would similarly be advantageous to provide a sheet buffering and inverting device that can be incorporated into a standalone printing system in order to ensure sheets are properly buffered and/or inverted prior to processing by a single printing engine.
In view of the foregoing disclosed herein are embodiments of a sheet buffering and inverting device. The device can each include a sheet transport path and multiple sheet inverter paths extending upward and/or downward from the sheet transport path. Selected sheets being transported through the sheet transport path can be diverted into the sheet inverter paths, can be held for a time (i.e., buffered, staged, etc.) in the sheet inverter paths, and can subsequently be fed back into the sheet transport path such that they are inverted. Optionally, additional sheet transport path(s) can branch off the sheet transport path upstream of the sheet inverter paths and can connect to the distal end of each sheet inverter path to allow sheets that do not require inverting to also be buffered. The device can be incorporated into a discrete module of a modular printing system in order to ensure sheets are properly merged and oriented after processing by multiple printing engines. Alternatively, the device can be incorporated into a standalone printing system in order to ensure sheets are properly buffered and/or inverted prior to processing by a single printing engine.
More particularly, embodiments of a sheet buffering and inverting device can comprise a sheet transport path extending, for example, essentially horizontally between a first location and a second location. The sheet transport path can receive a stream of sheets at the first location and can feed the stream of sheets towards the second location. Each of the sheets in the stream can initially (i.e., when received at the first location) have an orientation with a first edge comprising the leading edge and a second edge (i.e., the edge opposite the first edge) comprising the trailing edge.
A plurality of sheet inverter paths can be connected to the sheet transport path and can, for example, extend essentially vertically, downward and/or upward, from the sheet transport path. That is, each sheet inverter path can have a first end (i.e., a proximate end) adjacent and connected to the sheet transport path. Each sheet inverter path can further have a second end (i.e., a distal end) that is opposite the first end and, thus, that is located below or above, respectively, the sheet transport path. Each sheet inverter path can have a length sufficient to hold one or more print media sheets.
In one exemplary embodiment, the device can have multiple sheet inverter paths positioned either above the sheet transport path (i.e., upper sheet inverter paths) or below the sheet transport path (i.e., lower sheet inverter paths). In yet another exemplary embodiment, the device can have multiple upper sheet inverter paths positioned above the sheet transport path and multiple lower sheet inverter paths positioned below the sheet transport path. In yet another exemplary embodiment, the device can have a single upper sheet inverter path positioned above the sheet transport path and a single lower sheet inverter path positioned below the sheet transport path.
Additionally, each sheet inverter path can comprise a first gate, at least one sheet transport device, and a second gate. The first gate can divert a selected sheet from the stream being transported through the sheet transport path such that the first edge of the selected sheet enters the sheet inverter path rather than continuing along the sheet transport path. The sheet transport device can transport the selected sheet away from the sheet transport path at least until the second edge is fully contained within the sheet inverter path. The sheet inverter path can hold (i.e., buffer) the selected sheet. Subsequently, the sheet transport device can reverse directions, transporting the selected sheet back to the sheet transport path such it is inserted within the stream. This process can be guided by the second gate so that the orientation of the selected sheet is inverted, as compared to its original orientation within the stream (i.e., with the second edge comprising the leading edge and the first edge comprising the trailing edge).
Optionally, the sheet buffering and inverting device can further comprise one or more additional sheet transport path(s) branching from the sheet transport path upstream of the sheet inverter paths (i.e., between the first location and the sheet inverter paths). The additional sheet transport path(s) can connect to the distal end the sheet inverter paths to allow sheets that do not require inverting to also be held (i.e., buffered) in the sheet inverter paths. Finally, a controller that is operatively connected to the various sheet transport paths and sheet inverter paths and, more particularly, to the gates and sheet transport devices within such paths, can control sheet movement through the sheet transport paths and into and out of the sheet inverter paths.
Any of the sheet buffering and inverting device embodiments, as described above, can be incorporated into a discrete sheet buffering and inverting module. Such a sheet buffering and inverting module can comprise a frame having a first side and a second side opposite the first side. A sheet buffering and inverting device can be contained within and supported by the frame such that the sheet transport path extends essentially horizontally across the frame from a sheet input port on the first side to a sheet output port on the second side. Furthermore, one or more of these sheet buffering and inverting modules can be incorporated into a modular printing system, having multiple printing modules, in order to ensure that sheets printed by the multiple printing modules are properly merged and oriented prior to final output.
Any of the sheet buffering and inverting device embodiments, as described above, can also be incorporated a standalone printing system in order to ensure sheets are properly buffered and/or inverted prior to printing by a single printing engine. An exemplary stand alone printing system can comprise a printing engine (e.g., a xerographic printing engine, an inkjet printing engine, a solid ink printing engine, a bubble jet printing engine, etc.) and a sheet buffering and inverting device, as described above, adjacent to the printing engine.
For example, the sheet buffering and inverting device can comprise a sheet transport path extending from a first location to a printing engine and past the printing engine to a second location. The sheet transport path can further comprise a loop back connection back from the second location to the first location. A plurality of sheet inverter paths, each having a length sufficient to hold one or more print media sheets, can be positioned between the first location and the printing engine. Each of the sheet inverter paths can have a first end (i.e., a proximate end) adjacent to the sheet transport path and a second end (i.e., a distal end) opposite the first end. An additional sheet transport path can branch from the sheet transport path between the first location and the sheet inverter paths. This additional sheet transport path can connect to the distal end of each of the sheet inverter paths. A plurality of gates and sheet transport devices within the device can be selectively controllable so as to cause buffering and/or inverting of sheets by the sheet inverter paths prior to processing of the sheets by the printing engine. Specifically, a controller can be operatively connected to the gates and sheet transport devices and can control actuation of the gates and sheet transport devices in order to control movement of sheets into and out of the sheet inverter paths from either end and, thereby to cause buffering and/or inverting of the sheets, as necessary, prior to processing of the sheets by the printing engine.
These and other features are described in, or are apparent from, the following detailed description.